Other roads

Railways

Many of the lines around Ljubljana are done out as far as the Yahoo mapping goes. A few more bits still need doing

The 3 coach tilting EuroCity train between Ljubljana and Venice is really bad for GPS fixes. If you have a fix before you get on, an RFMD or SirfIII gps may get a lock at a few points on the trip, but will really struggle. If you haven't got a fix before boarding, it's not going to ever get one...

The GPS reception properties of the hauled coaches between Munich and Ljubljana / Zagreb have yet to be investigated.

Hiking and Bicycle Trails

Currently the "official" OSM feature list does not offer a satisfactory level of coverage for hiking and bicycle trails in the hills and mountains. There are several discussions and proposals on how to improve this, but there is still no agreement. Since hiking (and cycling) trail project have already started for Slovenia (see the map of Mariborsko Pohorje), a special page on suggestions and proposals on how to map trails in Slovenia has been created (Mapping Trails In Slovenia). This page also includes discussion on other related (ski trails and infrastructure, natural features etc).
Also check out Srtm2Osm tool.